壳聚糖类原油深度脱盐破乳剂的结构设计、合成与性能研究

With the industrial application of new technology in oil extraction, oil recovery percent increased, but the crude oil emulsification was aggravated and the contents of water and salts, especially the contents of oil soluble salts were elevated, making it increasingly difficult to break the emulsions. Therefore, it seems to be particularly necessary to develop a new type of high-efficiency oil demulsifier. Chitosan is abundant, widely available, environmentally friendly, and can be chemically modified easily. This study is to synthesize a series of methoxy polyethylene glycol(MPEG) grafted quaternized carboxymethyl chitosan, and characterize their molecular structure. The introduced carboxymethyl has strong chelating capbaility of metal ion. Simutaniously, quaternary ammonium salt group can adsorb negatively charged substances in crude oil. Thus, the zeta potential can be reduced and mutual electrostatic repulsion of oil droplets can be weakened, resulting in the dramatical decrease of the stability of interfacial film between oil and water. By changing the structure, position and the degree of substitution, a series of high-efficiency oil demulsifiers with the ability to remove oil soluble salts by chelating（i.e.， deep desalting） while demulsification for different kinds of crude oils can be expected.In this program, we will assess the demulsification and deep desalting properties of the synthesized demulsifiers on several crude oil samples of different properties, and investigate the mechanism of demulsification and desalting and reveal the effects of the molecular structure, such as the molecular weight, the degree of substitution, the size of hydrophobic group, the length of polyether side-chain and the aggregation structure on the demulsification and deep desalting properties of the demulsifiers. We hope that this research can provide theoretical guidance for the development of new environmentally friendly natural polymer demulsifiers and facilitate the oil extraction industry.

随着采油新技术的应用，原油采出率增加，但乳化现象加重，含水含盐量尤其是油溶性盐含量增加，破乳脱盐难度增大。开发新型高效破乳剂及脱盐剂显得尤为必要。壳聚糖来源广泛且环境友好，易于被化学修饰。本项目拟合成一系列聚乙二醇单甲醚接枝的季铵化羧甲基壳聚糖，进行相应的分子表征。引入的羧甲基对金属离子有很强的螯合作用，季铵盐基团可吸附原油中的带负电荷的物质，降低ζ电位，削弱原油液滴相互间的静电排斥作用，从而破坏油水界面膜的稳定性。通过改变各基团的结构、取代位置和取代度，可望得到一系列适合于不同性质原油的高效破乳剂，且能在破乳的同时螯合脱去油溶性盐（深度脱盐）。采用不同性质的原油样品评价其破乳脱盐性能，研究其破乳脱盐的机理，揭示其分子结构如分子量、取代度、疏水链段长度、聚醚侧链长度及聚集态结构等与破乳脱盐性能之间的关系，为新型深度脱盐破乳剂的开发提供理论指导，也为我国石油工业的发展提供技术支持。

随着采油新技术的应用，原油采出率增加，但乳化现象加重，含水含盐量尤其是油溶性盐含量增加，破乳脱盐难度增大。开发新型高效破乳剂及脱盐剂显得尤为必要。壳聚糖来源广泛且环境友好，易于被化学修饰。本项目采用三种自制的不同烷基链长的季铵盐与四种不同平均分子量的聚乙二醇单甲醚与壳聚糖或羧甲基壳聚糖进行接枝反应，合成了聚乙二醇单甲醚接枝的N-羧甲基壳聚糖、聚乙二醇单甲醚接枝的季铵化N-羧甲基壳聚糖及聚乙二醇单甲醚接枝的季铵化N,O-羧甲基壳聚糖破乳剂3个系列共40多种壳聚糖类天然高分子破乳剂，采用傅里叶变换红外光谱和核磁共振氢谱确定了其分子结构，研究了其溶液性质，建立了较为完善的分析方法。采用脱水原油室内配制的系列含水率不同的稳定的W/O及O/W型模拟乳液，并对该类破乳剂的物理、化学性质和破乳脱盐性能进行测试，评价了聚乙二醇单甲醚接枝的N,O-羧甲基壳聚糖及聚乙二醇单甲醚接枝的N -羧甲基壳聚糖的破乳脱除盐的性能，并初步探讨了其破乳机理，讨论了其分子结构、聚醚侧链长度、破乳脱水时间，脱水温度及破乳剂浓度与破乳脱水能力之间的关系。结果表明，本项目合成的壳聚糖类天然高分子破乳剂的破乳性能均优于市售的两种破乳剂。